Marin beaches get top marks for water quality in report for spring and summer

Beachgoers in Marin should have no reservations about jumping in and taking a dip as the weather warms — at least based on water quality.

The county's beaches have some of cleanest water in the state during spring and summer months, according to an annual Beach Report Card released Thursday by the environmental group Heal the Bay.

Analysts from the Santa Monica-based group assigned A to F letter grades to beaches as part of their annual statewide study, based on data on levels of bacterial pollution.

Heal the Bay gave an A or A+ to all 24 Marin beaches in its report.

"Marin County earned excellent water quality grades this past year during summer dry weather with all locations receiving 'A' grades," according to the report.

The water quality during wet-weather months is not consistently tested in Marin, however, so that is not accounted for on the report card.

"In the summer the water quality is generally very good," said Deb Self, executive director of San Francisco BayKeeper, a bay pollution watchdog group. "But the bay tends to have bacterial problems after heavy rains, and that is definitely true in Marin."

The rains wash pollutants into the bay, which worsens water quality. Marin County, as with most other jurisdictions, only has money to test between April and October, when more people are active in the water.

"We are encouraged by the excellent beach water quality in the Bay Area, specifically during the peak summer season," said Amanda Griesbach, a water quality scientist and lead author of the report.

But she added it's "important for local agencies to implement more wet-weather water quality improvement projects."

The report did note, however, that "there were no reported sewage spills in Marin County that led to beach closures this past year."

And beachgoers throughout the Bay Area can generally feel secure during the summer season.

Ninety-three percent of the beaches in Marin, San Francisco, San Mateo, Alameda and Contra Costa counties received an A for water quality. Those marks are an improvement from last year's report, when only 78 percent of Bay Area beaches earned A grades for the summer period. Statewide, 85 percent of 445 California beaches graded received A grades for the reported time period.